The present invention is directed to knob locking devices and, more particularly, is directed to a knob locking device which not only provides for the complete locking of the know without affecting the position of the knob setting, but also establishes variable amounts of drag on the knob to enhance the operator's fine tuning control of the knob to adjust the electrical component.
Several prior art arrangements are known to provide a locking device to securely hold a control knob setting on a variable electronic device or component. Two pertinent prior devices are shown in the Damon U.S. Pat. No. 2,833,158 patent and the Shalek U.S. Pat. No. 3,053,110. The Damon device is only a two position arrangement wherein the locking device is either in the locked position or the unlocked position. There is no ability in the device to provide variable drag on the control knob which is desirable in many cases when an operator is precision setting the component using the control knob. If the control knob is too loose or free moving, precise positioning of the control knob is very difficult. Therefore, placing a slight amount of drag on the control knob allows an individual to enhance his precise positioning of the control knob to accurately adjust the electrical component. Further, the Damon device is unnecessarily complicated in its construction, since it utilizes at least five separate parts which must be made and assembled to constitute the locking device.
The Shalek device is also somewhat complicated in its construction, since it requires at least four components to constitute the locking device. Further, the Shalek device does not provide for a locking directly on the knob, but rather acts as a biasing means on the control shaft itself. Further, because of the unnecessary complicated use of several parts to construct not only the Shalek device, but also the Damon device, the assembly of such locking devices is more costly and time consuming. This is a considerable disadvantage with respect to the efficient and economical production of control arrangements for variable controlled electrical components or devices.